charging lifepo4 batteries.

Themaskedwolf

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i have 3 40160s 3.2v 16ah batteries and want to hook up a charger to them.
as they are 16ah with 1cc charge current recommend i was looking for a charger that could fit my needs been searching around and was looking at http://factory.dhgate.com/charger/6.4v/10a-lifepo4-battery-charger-p44623238.html although i would have to worry about overcharge protection i was wondering if i needed a Protection board on the battery pack. this will be used to drive sst-90. not sure if i should just use 2 cells or in battery pack but as charging goes i've not seen a higher amp charger. i've seen a few 9.6v charger and few 3.2v ones but they are very low amps and would take more then 4 hours for one cell. to charge. any suggestions?
 

sunny_nites

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You are on the cutting edge here. Doesn't appear to be a lot of experience with Lifepo4s around. I have used them to a degree ie. aa size with standard charger that came with the set of batteries and don't have much experience other than to say they appear to run as specified.

Also, the link you specified appears to be suspect. My link detector lit up when I tried to access it.
 

BVH

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It's a fantastic charger but to get all that power out of it with Lithium batteries they must have balance taps and it must be balance charged. It's kinda geared for the Prismatic packs that the RC people use. I have a bunch of them for my flashlights and power supplies so I use it all the time. They just came out with its' little sister, a PL6 that will do 30 Amps, IIRC.
 

Shadowww

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Or Turnigy MEGA 400W V2 if you're on budget - it supports up to 20 amps as well, but it's almost 2 times cheaper (at ~$80 shipped).
Note that you'll need hell of a power supply to power any of those chargers - a good option would be modern ATX12V PC PSU.
 

OrBy

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I charge my home made 2s LiFePO4 Airsoft packs using a iCharger 106B (http://www.jun-si.com/EnProductShow.asp?ID=89) powered by a RC hobby power supply. Slow charging is suggested to be 1.5A and fast charging at 5A from the a123 systems specifications sheet for my 18650 cells. (so fast charge is done in like 5-6min). I do balance charge them but I just run them till the gun starts slowing down then swap em out. (so no low voltage protection) If you do run them too low you will harm em a little but they wont go boom - you will just loose some capacity. I do also have some Tenergy brand RCR123A LiFePO4 cells I am testing out in some lights but they came with their own charger that outputs 250ma so I just use that for them and when they start to go dim swap em out.

For a huge 40160 cell though you could likely dump up to 80A into them to speed up your charging time before you start to damage them. Good luck pulling that off without some sort of custom solution. You could try a higher end hobby charger like an iCharger 306B (http://www.jun-si.com/EnProductShow.asp?ID=100) but that will only get you up to 30A max and you would still need to find a REALLY beefy power supply (or a few hooked together) to get that going... The nice thing about these hobby chargers however is there is no need to worry about overcharging as they will stop when the cell is full and you can do more then one cell at a time (6 or more depending on the model) if you wire it up correctly to the balancing connector.

Just a warning - once you start going up to these current levels you need to make sure you are using the correct gauge wire and quality connectors or things can start melting. Also LiFePO4 are not much of a explosion or vent/fire risk if abused but if you manage to short them they will get VERY hot and what ever you short them with will weld it self in place and get white hot. So even though the batteries themselves are safer - they still carry their own risks to be aware of.

A good resource for more info about this kinda thing can be found over @ http://www.rcgroups.com/batteries-and-chargers-129/ as they have been using LiFePO4 for a while now.

Oh and that 1412 charger looks like junk - I have never seen it before but I would not take the risk.
 

LEDAdd1ct

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Accidents never happen with proper LiFePO4's (like A123), they are safe chemistry.
But it could kill the cells or degrade them hugely...

No, no, no—that wasn't a criticism leveraged at LiFePO4 cells, that was a criticism directed towards the "will charge everything and do your laundry" cradle charger posted above. :)
 

Shadowww

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For a huge 40160 cell though you could likely dump up to 80A into them to speed up your charging time before you start to damage them. Good luck pulling that off without some sort of custom solution. You could try a higher end hobby charger like an iCharger 306B (http://www.jun-si.com/EnProductShow.asp?ID=100) but that will only get you up to 30A max and you would still need to find a REALLY beefy power supply (or a few hooked together) to get that going... The nice thing about these hobby chargers however is there is no need to worry about overcharging as they will stop when the cell is full and you can do more then one cell at a time (6 or more depending on the model) if you wire it up correctly to the balancing connector.
Not all LiFePO4 cells support 5C charge, in fact, I've only seen A123 ones that do. Most LiFePO4's have recommended charge current of 0.7C and maximal charge current of 1C. So I wouldn't pump any more than 20 amps into that 16 Ah cell, in fact, if I had one myself I'd more likely charge it at 10A or so.
No, no, no—that wasn't a criticism leveraged at LiFePO4 cells, that was a criticism directed towards the "will charge everything and do your laundry" cradle charger posted above. :)
Ah, I see. sorry :)
 

OrBy

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Not all LiFePO4 cells support 5C charge, in fact, I've only seen A123 ones that do. Most LiFePO4's have recommended charge current of 0.7C and maximal charge current of 1C. So I wouldn't pump any more than 20 amps into that 16 Ah cell, in fact, if I had one myself I'd more likely charge it at 10A or so.

Valid point there - I have only seen spec sheets for the a123's system's cells. If that's the case even a smaller hobby charger with power supply would suit these just fine then. A 15A-20A supply (for a bit of leeway) and something like my 106B could speed up his charging and do all 3 of his cells at once if wired up to the balance connector. If you shop around you could likely find that all for under $100.
 

lemlux

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The Headway 16Ah LiFePo4 40160's have been discontinued according to Headway Headquarters. The largest now offered are 15Ah 40152's. I have considered charging 4S multiple blocks of 40152's using (a) cell to cell balancing connectors designed for 20Ah lower discharge / charge rated prismatic battery packs. I would use one or more CC/CV/pulse 3 cycle stock charger that are available in fixed at 4S, 8S, 12S, 16S, 20S, 24S, 28S and 32S sizes. Here's a link to the balancers which are not cheap at about $8.95 @.

http://elitepowersolutions.com/products/index.php?cPath=42&osCsid=bd59f15c1a982d154c7588ee6768108b

Here is data covering LIFEPO4 chargers sold by the same company.

http://elitepowersolutions.com/products/index.php?cPath=9

I'm considering building an ebike powered by a nominal 84V with 28S 40152 cells. I'd spread the cells around the bike in a 12S bundle plus a 16S bundle. I'd charge the two bundles separately with TSL36-6 and TSL48-6 Chargers, respectively.

I'd depend upon a TBD low voltage cutoff for the 28S power source and be willing to replace bad cells as they occur. My useage and willingness to measure discharge current makes the use of a BMS problematic.
 

VegasF6

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Accidents never happen with proper LiFePO4's (like A123), they are safe chemistry.
But it could kill the cells or degrade them hugely...

They are a safER chemistry than some. All batteries including A123 are subject to failure.
Subjected to overcharging or overheating A123 batteries absolutely will explosively decompress.
 

Shadowww

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They are a safER chemistry than some. All batteries including A123 are subject to failure. Subjected to overcharging or overheating A123 batteries absolutely will explosively decompress.
Uhm, how high overcharge are we talking about? I've once overcharged pair of my A123 18650's to 4.2V (instead of normal 3.6V) when I left my charger on Li-Ion setting before putting them in, but they didn't exploded, and, in fact, still are going perfectly.
 

VegasF6

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Yes, I guess it would take more than that as I have read of other people doing the same thing charging to 4.2 though that's still no guarentee of safety. I would imagine charge current and temperature would be a factor in those cases. Simply google A123 fire and Chevy Volt fire, check the RC forums etc. The results aren't the same as with a lithium cobalt chemistry battery but pump enough energy into a battery and it will pop. A hobby charger or automotive environment are capable of that energy. I don't think it's correct to make statements like "accidents never happen" when referring to these cells.
 

OrBy

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I did a google search like you said VegasF6 - all I got was links on how when crushed or abused A123 System cells do nothing (not even smoke). But when they are shorted - they do cause fires because what ever shorts them gets so hot it ignites. Like with all the Prius/Volt and other EV fires in the news the cells are not causing the fires - it's improperly made cooling systems or physical braces causing the fires after shorting the cells. I think that's kinda like blaming the gas for a fire when it was the match that lit it or a gun hurting some one and not the person pulling the trigger. Now I am not saying they could never have an issue but they are the most stable cells I have ever used/abused.
 

BVH

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I once had 10S Power Tubes filled with DeWalt A123's. I paralleled 5 of them for about 11 AH to run my 28 Volt, 16 Amp Locator - so a 1.5C load. I did not run the light anywhere near the time required to deplete the cells, yet a few moments after shut down, a couple of the cells "poofed/vented" without flames, of course. I was surprised with such a small load.
 
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